The present invention relates to guide wire introducers which are medical devices for the insertion of a guide wire into the blood vessel of a patient.
Guide wires are used so that a cannula which is mounted over the guide wire can be slidably moved along the guide wire for insertion into the blood vessel of a patient. The guide wire is subsequently withdrawn from the blood vessel through the cannula leaving the cannula within the blood vessel.
Known guide wire insertion devices or introducers suffer from problems arising from the difficulties of manipulation and the exposure of the guide wire to possible contamination prior to insertion into the blood vessel. Obviously, it is important to be able to manipulate the guide wire into the patient""s blood vessel with a minimum of tedious manoeuvres while, at the same time, it is important to isolate the guide wire from any contamination during the process to prevent that contamination from entering the blood vessel of the patient and do harm to the patient.
In a currently available guide wire introducer, access to the blood vessel of the patient is first established using a percutaneous needle introducer with an attached syringe. Confirmation that the needle has pierced the blood vessel is established when blood can be seen freely aspirating into the syringe. The syringe is then removed which requires a change of grip on the introducer and increases the chances for misplacement of the needle tip which might cause damage to the blood vessel wall, blood loss, air embolism and increased procedure time. Subsequently the syringe is discarded. However it may contain aspirated blood which poses the potential risk of contamination or harm to the attending personnel especially if the syringe plunger is depressed accidentally. In such case, the patient""s blood can contact the personnel and pose a health risk to those persons.
The guide wire itself is normally provided in a coiled, protective tube. The diameter of the coil assembly is bulky and can hinder access to the introducer. This known guide wire introducer uses a J tip Seldinger guide wire which has its end formed into the shape of a J. That configuration has to be straightened before introduction into the needle. This is normally achieved by pulling the wire backwards into a straightener and then moving the wire forwardly into the desired location within the patient. Manipulation of the guide wire through the straightener and needle introducer involves a high degree of care and experience.
The whole introduction procedure may require assistance by nursing staff as additional hands are often required to hold the introducer needle in the blood vessel whilst straightening and advancing the guide wire.
It is an aim of the present invention to provide a device for advancing a guide wire into a blood vessel of a patient which removes or mitigates against the disadvantages mentioned above in connection with the currently available guide wire introducer.
According to the present invention, a device for advancing a guide wire into a blood vessel of a patient comprises a housing from a distal end of which extends a needle hub support having a blood aspiration canal extending along its length; a syringe chamber located in the housing; a passageway extending between the blood aspiration canal and the syringe chamber for the passage therethrough of aspirated blood; a switch mounted for sliding movement along a surface of the housing and having attached thereto a cannula for movement therewith; the switch being formed with a through hole aligned with the cannula and the blood aspiration canal for the passage therethrough of a guide wire; the arrangement being such that movement of the switch towards the distal end of the housing will cause the cannula to block the passage of blood along the passageway between the blood aspiration canal and the syringe chamber.
In a preferred embodiment a seal is provided preventing the flow of aspirated blood along the blood aspiration canal and over the housing, movement of the switch towards the distal end of the using causing the cannula to pierce the seal to allow the passage of the guide wire through the canal.
In a preferred embodiment, lugs are provided on the surface of the housing one at the distal end and the remaining lug at the proximal end of the housing, each lug being formed with a through hole in alignment with the through hole in the switch for guiding the guide wire.
Preferably, the switch is slidably mounted on rails formed on the housing between the lugs and over said surface which is substantially flat.
In a preferred embodiment a flexible envelope is attached to the proximal end of the housing and surrounds that portion of the guide wire extending outwardly from the proximal end of the housing. Thus, the guide wire is protected from contamination by the flexible envelope.